Pump



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R. P, MILLER Jan. 3l, 1939.

PUMP

Filed oct. 2e, 1935 3 Sheets-Sheet 1 Yuan Jan. 31, 1939.

R. F" MILLER PUMP Filed Oct. 26, 1935 5 Sheets-Sheet 2 IN VENTOR.

BY Rum' ATTORNEY.

R. P, MILLER PUMP Filed octvl 26, 1955` 3 sheen-sheet 5 INVENjroR. elfZZ r,

ATTORNEY.

Psreafed Jan. 31, 1939 UNITED STATES PATENT o FFicE PUMP Robert P. Miller, San Gabriel, Calif., Application October 26, 1935, Serial Noawlld i 26 claims. iol. 10s-241i forced through the conduit by a uid piston oi!" the pressure uid; and it is the objectof the invention to positively control this alternate admission of iluids, independently of theirpressure differential.

More particularly the invention relates. to that type of pump wherein a valve, generally designated a foot valve, controls admission to a conduit of the fluid to be pumped, and a valve, generally designated a head valve, controls admission of pressure fluid to the conduit. 'When the foot 'valve is open the head valve is closed, thereby' This is the lling period; The foot valve is then' closed. and the head valve is opened. Pressure fluid supplied to the conduit,viathe open head valve thus displaces the volume of'iluid to be pumped, which has been trapped in the conduit volume of fluid is thus forced through the conduit. This is the discharge period. The head v alvesis then again closed and the foot-valve opened, so that the cycle of operation is repeated.

Heretofore there have been pumps of this typev wherein the head and foot valves have been connectedfor dependent operation by pressure differential between the displacing fluid and the iiuid to V4be pumped. In such constructions the fluid to be pumped, seeking its static level, opens the foot valve and thereby closes the dependently operated head valve. The fluid to be pumped,

thus entersthe' conduit during uns filling period, and when the pressure of this fluid against the foot valve is balanced, the pressure fluid opens the head valve and thereby closes the dependently operated foot valve. During the discharge period stituting the fluid piston, is free to expand, andv its pressure against the foot valve is thereby reducedso that the pressure ofthe main body .of

' mission of energy'via the conductor. with this last fluid to be pumped, again seeking its static level,

reopens the foot valve and thereby again closes the dependently operated head valve. The nlllng period is thus again inaugurated and the cycle oi operation is repeated.

In the present invention, while in order to produce the filling period the displacing fluid must have a pressure less than that of the huid to be pumped, the head and foot valves are not dependentiy and automatically operated merely by this pressure differential as in pumps of this type heretofore employed, 0n the contrary; the head valve is controlled by operating means which is preferably in the conduit through which uid is to be pumped, and which operating means is preferably adjacent the head valve. The operating means may include a driven` element connected to the stem ofthe head valve, with actuation of the operating means preferably controlled, not by mechanical connections such as links or rods, but by energy of a type which may be transmitted via a stationary conductor, e. g., electrical or fluid pressure energy, and if fluid pressure is employed it is other than merely the aforemenf tioncd pressure diierential. In similar manner the foot valve, if so desired, may be controlled by operating means which may be in the' conduit .through which fluid is to be pumped, and which above the closed foot valve; and this trapped operating means may be adjacent the ioot valve. Actuation of this operating means is preferably controlled by energy such as electrical or duid pressure energy, other than merely the pressure differential between the displacing uidsand the fluid which is to be pumped. Consequently, While it is essentialthat the diplacing fluid be regulated so that its pressure is not in excess oiGthat of the fluid to be pumped, seeking its static, level duringr .the filling. period, still the cycle of operation is in' no way dependent upon ,accurate adjustment of this pressure differential as is required when the head and foot valves are dependently and automatically operated merelyby this pressure sure ofthe fluid to lbe pumped and/or the Vpressure of the displacing fluid, as are liable to occur in practical operation of a pump of this type. y

More particularly it is an object of the invention to preferably' control actuation of the valve operating means by that type of energy which may be transmitted via a stationary conductor. with said conductor leading from the valve operating means` to a means which-controls transvalve operating means.

It is a still further object of the inventionto preferably employ a control which automatically functions to provide the alternating filling andA discharge periods, and to preferably adapt the automatic control for adjustment to produce a filling period and a discharge period, each of which is of desired interval.

The invention, while of general application, isd particularly adapted to lift pumps, since the valvular means for controlling admission of fluid to the conduit through which :duid is to be pumped, and the operating means for said valvular means may be conveniently submerged in the fluid which is to be pumped, by suspending. these parts from a string of pipe which is lowered into the fluid, preferably with a conductor for transmitting the energy which controls Athe operating means, leading to acontrol at such level higher than the submerged parts of the pump, as will make it conveniently accessible for adjusting the cycle of operation.

By Way of illustration, the invention is shown embodied in a pump for an oil.wel1, in\ which case the fluid to be pumpedAs the flow from a production stratum in the bore of the well, with said flow including both gas and liquid constituents, and the displacing pressure fluid may be compressed gas, preferably from a. suitable source at the earths surface. For vbrevityin distinguishing these fluids they will be hereinafter referred to als production fluid and pressure fluid, respec- .'Ihe conduit through which production fluid is elevated by the pump is preferably a usual productionstring lof well tubing extending through usual well casing, and the pressure fluid is supplied to the pump either via a seprate tubing located inside or outside the well tubing but inside the well casing, or maybe stored in the annular space between the well tubing and the well casing, above a suitable packer, from )whence it is supplied to the'pump. Il

a Further objects of the invention will be readily ,understood from` the following description,l

of the accompanying drawings, in which:

Fig. 1 is a diagrammaticI illustration of the invention, showing the'pump and a remote con- Fig. 2 is a detail axiall section'` through the pump.

Fig.` 3 is a transverse section on the line 3-3 of Fig. 2.

Fig. 4 is a view similar to Fig. 2, showing'a modiedI construction.

Fig. 5 is a similar view, showing a still fur-v ther modiflcation.

Fig. 6 is a similanview, showing a dierent type of operating means for the head valve.

Fig.- 7 is a -view similar to Fig. 1, showing a still different type of operating means for the head valve. Y

Fig. 8 is a similar view, 'showing a still different type of valve operating means.

Throughout the drawings, and as `an instancev of the construction when the pump is employed in"`an oil well, usual well casing is, shown at I, having a string'of usual production tubing 2 suspended therein so as to form an aniular space 3 between the tubing and the casing. Production iluid from the well is admitted through the' lower end of the casingA into the lower end of the tubing stringin usual manner (not shown), and

. rises thence-through a tail-piece 4 atth lower 9,145,402 mentioned control preferably remote from the end of the tubing string. The production fluid rises in the production string preferably into a tubular housing which is includedin the tubing string above the tail-piece, and which is -run preferably in with the tubing to alevel where a foot valve in the production string, preferably'in the tubular housing, is submerged in' the production fluid when the latter rises to its static or working levelin the tubing string.

In the illustrated embodiment of the invention, the production fluid is pumped through the tubing 2 to the earths surface, and the pressure uid which operates the pump is preferablysupplied to and stored \in the annular space 3, from whence it is admitted to the production string, preferably at the tubular housing of the pump, viaa suitable intake. A packer shown diagrammaticaliy at 'I, is placed between the tubing `2 and the casing I below this intake, to prevent the stored volume of highly compressed pressure fluid from leaking into the production stratumA of the formation.

At the top of the well the tubing 2 is connected to a usual head 8 having avdischarge conduit 9 municating at its lower end with the tail piece 4 via a foot valve; and a head valve is mounted in the production string, preferably at the upper portion of ther tubular housing and controls ad-A mission` of iressure uid from the annular space 3 to the lower portion of the expansion chamber. Operating means for the head valve is preferably also mounted in the production string, preferably in the tubular housing and its actuation preferably is controlled by energy transmitted 'via a stationary conductor which may extend upwardly,throughthe annular space 3 to the top of "the well and vthence to suitablecontrol mechanism.

Referring to Figs. 1 and 2, the tubular housing which is incorporated in the tubing string 2, is

' shown at 5, yand the head valve 'is shown at I4,

mountedin a valve housing I5. 'I'he housing I5 may be suspended in the tubular housingni by means o'f a nipple I8 at the upper end of thel housing` I5, connected to a conduit I9 which is preferably integral with thatl length of the tubing 2 which is next above the housing 5. The

upper end of the conduit lil'extends laterally to thewall of Vtubing 2 and opens therethrough,

preferably at a plurality f screen slots 20, sov

rfo

with -the valve stem for opening the head valve. 'Ihe foot valve is shown at I3, mounted in the lower end of the housing 5.

The'operating v means opens the head valve and holds it open fora predetermined discharge `tion iluid, until the operating means period, actuation of the operating means being independent of pressure differential between the pressure iluid and the production fluid, and at the end of the discharge period the operating means 'is rendered inoperative to hold the head valve open, this operation being also independent of pressure diierential between the pres- `sure uid and the production iluid. The head t valve is then closed, either by thev operating means being actuated in the reverse direction, or simply by a force such as spring tensi'on, sui'- cient to close ,the head valve when the operatn ing means has been rendered inoperative to hold it open. The head valve then remains closed for a predetermined lling period, being held against opening,irrespective of pressure difieren'- tial'between the pressure fluid and the producis again actuated toi, open the head valve.

'I'he foot valve closes just prior to or at the time when the head valve is opened by its operating means, and opens at the time or preferably just after the head-valve closes, so that the pressure 'fluid which is admitted to the production string when the head valve is opened, does not force the production fluid back intothe formation. For this purpose operating means may close 'the foot valve at the proper time, or it may simply close responsive to pressure dierential between the pressure fluid'and the production iluid; and the foot valve may be -opened by a spring or other suitable means, or it may simply open responsive to the production fluid" again seekingits static level after the force of the pressure iluid has been relieved. l The operation ofthe pump is as iollowsz' The housing 5 is run into the well casing until the foot valve I3 is submerged below the static or lworking level of the production fluid,l and with the packer 'i shutting 0E the' production fluid from the annular space 3, pressure fluid is supplied to and stored in this annular space. At the start of the nlling period the operating means for holding the head valve open has been rensuncient to ll `the production string with pro- ,1

duction fluid to a level which may be several iiundredfee't up the tubing 2, and without relying j upon pressure differential between the pressure fluid labove `the closed head valve and the production fluid in the expansion chamberpthe op'- erating means for the head valve is actuated to open the head valve, just prior to or atv the time a+. which the footvalve is'moved to its closed position, either by a separate operating means or by the increased pressure above the foot valve.

Pressure uid is thus suppliedy to the-produ'ction string via the port 22, and production fluid having been trapped in the production string above theA closed foot `valve, the pressure yfluid `forms a fluid piston beneath that volume of production iluid which stands in @the tubing 2 above the port 22,'and 'therebyy lifts said volume of production fiuid'throgh th'e tubing-string 2, for discharge at theconduit 9. During thisY discharge period the operating means holds the head valve open for a predetermined interval determined by a control means which renders the operating means inoperative at the end of the desired ,period softhat the head valve then closes, but with said closing of the head valve in no way dependent upon pressure in the tubing string being reduced as a result of the load being relieved when the production uid has been elevated and discharged. The control means thus terminates the discharge period after a predetermined interval suiilcient to elevate and discharge the production uid through conduit 9, e. g., into a gas separator, and with the head valye then again closed and the foot valve openfthe flllingperiod restarts and the cycle of operation is repeated.

1 nate in 4a plunger 26 of a solenoid, the coil of which is shown at 2l, suspended from the valve housing l5. The valve housing has a passage'- way 29 at its intake side ,whereby the pressure of the displacing fluid which is supplied via nipple vill is balanced against the head valve, and an annular passageway 29 'at the outlet side of the valve housing extends downwardly to the annular port 22 so as to position said port below the 'head valve in order to prevent production fluid coming in contact with the head valve, there being sufficient leakage of pressure iluid past the head valve to ke'ep the annular space 29 full of pressure fluid at all times. ingly close the balanced head valve.

lThe solenoid -Z'l is preferably an iron clad solenoid, i. e., on'e in which the coil windings are completely surrounded by magnetic material; and in order to conserve space the housing E preferably forms a partof the magnetic circuit. The coil winding is preferably hermetically sealed, with an annular' space between its outer sealing means and the surrounding housing 5, so that this yannular space is a part of the expansion chamber t, permitting passage of the production uid.

As an instance of thisarrangement the core of the solenoid includes en'ds 32--33 of magnetic material such as mildsteel, connected by inner and outer tubes 36-35 having the coil 2l therebetween. The bore of the inner tube 3d receives the solenoid plunger, and the outer tube 35 encloses the coil 2li and is radially spaced from the surrounding wall of the housing 5. The tublesl 34-35 are welded or otherwise secured to the core-ends 32e-33;; and the coil assembly as preferably suspended from the valve housing i5, as for example by a threaded coupling 3t`having A spring 30 may yield-,

right arid ieft hand threads, with a pin ai aiining the parts. The tubes 3,5--35 are oi non-magnetic material, preferably stainless steel, and lugs 38 of magnetic material project from the core- `ends 32-33 for sliding contact with the housing 5 which is of magnetic material. AIt is thus the housing 5 and notthe outer tube 35, which completes the closed path of magnetic-material `for the magnetic circuit.

By their pressure tightconnec'tionswith 'the core-ends the tubes3435 seal the coil winding 2l against external or internal pressuregand consequently there is no need to pack o around the valve stem 23, the pressure from the passageway 28 being free to enter the bore of the tube 34 viaxv a screen 39. By utilizing the-housing i, rather than the outer tube 35, for the magnene circuit, the tube u muy be of night thickness occupying Ybut little space, and magnetic leakage from the plunger of the solenoid adjacent 'the working air gap is appreciably reduced, there- `by increasing the pull exerted by the solenoid. Furthermore the tubes 34 and 35 being of the same material, their expansion and contraction will be equal soas not to break their connections with the core ends 32-33; and expansion and contraction is provided for by the lugs 3l freely sliding in the housing 5.

The foot valve I3 of the pump is mounted in lthe housing below the solenoid 25-21. A spring 40 -shown as abutting the lower core-end 33 may yieldingly seat the foot valve, permitting the foot, valve to open responsive to pressure of the production fluid seeking its static or working level while the head valve is'closed during the lling period, and the spring closes the foot valve yin the expansion chamber above the foot valve,

when the tension of the spring combined with the static pressure of the column of production uid' exceeds the pressure exerted upwardlyr against the foot valve by the production fluid rising through the tail piece 4. A spring is preferably employed which w'ill close the foot valve when the production uid has risen to approximately its static level, and the operating means from a source of electrical energy "-44, the

for the head valve I4 is preferably timed to not open the head valve until just after the spring 40 has closed the foot valve, so that by the time the pressure fluid is admitted' to the production string the foot,valveis already closed, thereby avoiding excessive shockas might result if the foot valve did not close until downward pressure of the pressure fluid were exerted thereon, and also preventing the pressure fluid exerting back pressure, against the production stratum of the well. f

A control is provided for the solenoid 25-21, preferably a remote control at the top of the well; and for this purpose a cable 42 may provide the conductor for transmitting electrical energy to the coil winding 21 and may extend through the core-end 32 and the valve housing I5, and thence through the passageway 23 and the conduit I 9,

into the annular space 3 and thence upwardly along the tubing string 2.

'Ihe control may be any desired means for completing an electrical circuit and thereby energizing the solenoid for opening the head valve and holding it open throughout the discharge period, and then breaking the electrical circuit so as to deenergizel the solenoid and thus permit the spring 3|! to close the balanced head valve throughouty the filling period., The control means is preferably automatically operated to provide these ralternating .filling and discharge periods, and is preferably adjustable to -vary said periods, with the adjustments for the respectiveperiods preferably independent of one another. Y

A preferred type of control means is shown diagrammaticallyatFig, 1. `Wires 43-44 lead electrical energy being D. C., and suitable means (not shown) being employed to convert A. C. to D. C. in those cases where only A. C. is available. Wires 41-43 provide a circuit for the coil nected to the tubing 2 on Awhich the other side of the con 21 is grounded. The wireruccu-v nected to the wire 43 via a switch 4|,and when.

- period.

the switch is closed a circuit is completed for eni ergizing the coil 21 and opening the head valve I4 for the discharge period, and when the switch 49 is` open this circuit is broken, thereby deenergizing the coil 21 so that the head valve then closes for the filling period. Opening and closing the switch 49 may be controlled by timers A and B.

The timer A may be adjusted to provide a discharge period of any desired time interval, and the timer B may be separately adjusted to provide a filling period of any desired time interval. As an instance of this arrangement the timers/may each include Aa switch 5I and a cooperating swinging arm 52. The arm 52 is adapted for rotation clockwise by a shaft 53 which is continuously driven at constant speed by suitable means such as an electric motor (not shown) and clockwise rotation of the arm 52 is started and. stopped by an electro-magnetic clutch 54.` AWhen the arm 52 has been rotated clock-wise a predetermined distance as shown attimer B, it engages and opens its cooperating switch 5I, and the circuit for its electro-magnetic clutch is thereby broken so that the clutch from its inoperative position to the pointwhere it opens its cooperating switch is thus varied at will, for regulating the time interval during which the timer functions, and the knobs 55 of the respective timers A and B,`thus provide for independently adjusting the timers.

'I'he timers are alternately operated, i. e., their electro-magneticA clutches 54 are alternately engaged, as for example by an automaticmeans,

which is shownas including contractors C and D; and during thetime intervals when the timers A and B are respectively' operating, the'se contactors keep the switch 49closedi and open respectively, so as to` provide the discharge period and the lling period.` As an instance of this arrangement each contactor has a contact 56, with the contactor C also controlling the switch 43; and each contactor is operated by a coil 51. When the coll of contactor C is energized it opens its contact 55 and closes the switch 49, and when deenergized it closes'its contact 56 and opens the switch 43. When the coil of contactor D is en- 'ergized it opens its contact 58. and when deenergized it closes its contact. The contactors and the timers are electrically connected Vso th'at when the coil of one contactor is energized the `coil of the other is deenergized, and the coils of the contactors are Arespectively energized throughout the filling period and the'discharge For this purpose ythe wires u u lead to the B respectively, and at their Nopmisite sides the clutches of the timers 'A and'B are respectively connected to the contacts 55 of the contactors D and C as shown at\ Gli-6|.. Wires 52-63 respectively connect the wires 43 -44 to the contactors C and D, so that the contactor C controis the main operating circuit for the coil 21 via the switch 49,*and vila its contact 55 conelectro-magnetic clutches 54 of the timersl A- and l trois the circuit forA the electro-magnetic clutch of the timer B, while the contacter D, via its contact 56, controls the circuit for the electro-magnetic clutch of the timer A. The coil 51 of con: tactor C is connected to the wires 43-60, via a wire 64 and the switch 5I of the timer A, and in similar manner the coil 51 of contactor D is connected to` wires 44--6I, via a wire 65 l'and the switch 5I of the timer B.

The wiring diagram shows the positionvof the parts just as the. end of the iilling period is approached, the coil 51 of contactor C being de- 'energized as a result of the contactor 56 of the contactor D being open, thereby opening the*y switch 49 so that coil 21 is deenergized and the head valve I4 is closed for theI lling period. 'I'he coil 51 of the contacter C being deenergized, its contact 56 is' closed, thereby energizing the coil 51 of the contacter D to open its'contact 56. 'I'he circuit for the electro-magnetic clutch 54 of the timer A is thus broken, so that. its arm 52 remains stationary in its retracted position as shown, and at the same time the circuit for the electro-magnetic clutch 54 of the timer B is closed. The arm 52 of the timer B is thus rotated clockwise to the position shown in the diagram, and the time which it takes for the arm to rotate to a position where it nally opens its cooperating switch 5I determines the filling period. -When the switch of timer B is thus opened after a predetermined time interval, the coil 51 of the contacter D is deenergized so that its contact 56 closes. This energizes the coil 51 of the contacter C, closing the switch 49. The coil 21 is thus energized, opening-the' head valve I4 and starting the discharge period; and the closed contact 56 of the contactor D also energizes the electro-magnetic clutch 54 of the timer A, thereby causing clockwise rotation of the arm 5I of the timer A. 'I'he contact 56 of the contactor Cis also opened as aresult of its coil 51 being energized, thereby breaking the circuit for the electromagnetic clutch of the timer, B so that its arm 52 is returned to its retracted position by its spring (not shown), with its cooperating switch 5I then reclosing, and the retracted arm of the timer B then remaining stationary during the discharge period. The rotating arm 52 of thetimer A finally engages and opens its cooperating switch 5|, the time interval before this occurs determining the discharge period, and as a result of the switch 5I of the timer A being thus opened, the coil 51 of contacter C is deenergized, reclosing its'contact 56 and opening the switch 49. The coil 21 is thus deenergized so that the head valve I4 closes to again start the lling period, and the electro-magnetic `ses clutch 54 of the timer B is reengaged to again cause clockwise rotation 'of the arm 52 of the timer B. The coil 51 of the contacter D is also energized as a result of the contactv 56 of the contactor C closing, thereby opening the contact 56 of the contactor D. The electro-magnetic clutch 54 of the timer .A is thus disengaged so that the arm 52 of this timer Ais retracted byits spring, and the 'switch 5I of the timer A thus recloses and the cooperating arm 52 then remains stationary in its retracted position during the illling period. The parts are then 4again in the Vposition originally described, so that rotation of thearm 52 of the timer B lagairrcontrols the filling period. f y

At Fig. 4 a modiiication of fthe invention is shown, particularly applicable to'a welll struc ture wherein it may be desired to position the foot valve an appreciable distancev below the packer 1. This packer must be placed above the level at which the well casing is open to the surrounding formation, in order to prevent escape of pressure iluid from the annular space 2;

and the intake whereby this pressure iiuid isK directed into the valve chamber of the head valve must vbe above the packer. If then it is desired to position the foot valve at a muchlower level but at the same time admit the pressure fluid to the production string at a level which is only a comparatively short distance above the foot valve, it is necessary, with the structureshown at Figs. 1 and 2,'to suspend the head valve housing and its operating means an .appreciable distance below the conduit I9, as for example by elongat- 'ing the `connecting 4nipple which is provided at ythe upper end of the valve housing. This necessltates the cable 42 being' threaded through this elongated nipple in order that it may be connected to the coil 21. But with the structure shown at Fig. 4 only a short length of the cable need be threaded through the housing for the head valve, even though the foot valve is to be L positioned at a level far below that oiy the' packer 1.

As an instance of this arrangement, thecony the actuating solenoid 26a-21a, which may be similar to that previously described except that it is inverted, and which has its parts indicated by reference numerals 32a, 33a, etc., is mounted in the housing 5a above the valve housing I5a, and is connected to the valve housing by a coupling 36a. I'he head valve I4a is a. balanced valve, closed by a spring 30a and opened by its cooperating solenoid when the latter is energized, and the cable 42a for the coil of the solenoid extends through the valve housing I5a and the conduit I6a, and thence-into the lannular space 3 and upwardly along the tubing`2 so that it may be connected to a control means such as previously explained in connection with Figs. l and 2. The outlet side of the head valve has a depending passageway 29a terminating in a nipple 10, from which a conduit -1I of any desired length may be suspended so as to form a A discharge 22a through which pressure iiuid may In the modification oi' the invention shown at Fig. 5, the head valve and the solenoid for actuating the same, are mounted in housing 5b and comprise an assembly the same as illustrated at Figs. 1 and 2 and denoted byreterence numerals I4b. 26h, 21h, etc., but the foot valve, which is shown at Ilc, 'has a positive operating means'for closing the foot valve -at any desired time. As an instance vofthis arrangement the foot valve may be electrically operated, as for example by a Thefoot-valve is shown 4 and providing a balanced valve, with the'outletv of the valve housing communicating with the expansion chamber 6b as shown at '18.` The stem l1 of the foot valve projects upwardly through a screen 18 and terminates in the plunger of a solenoid; and a spring 8| yieldingly opens the footvalve for the ililihg period, and the solenoid when energized closes the foot valve for the discharge period.

The solenoid for the foot valveis preferably a structure similar to that of the solenoid assembly for the head valve which is shown at Figs. 2 and 3,. except that it is inverted. Its core-ends 32e- 33e are connected by inner and outer tubes Sic-e of non-magnetic material, enclosing the coil winding 21e which actuates the plunger 280;A

and the solenoid assembly is. supported upon the valve housing Il by a coupling 36e, and has lugs 38e slidably engaging the wall oi housing 5b so that the latter forms a part of the magnetic circuit. The solenoid for the toot valve may be controlled by the same type of controlmeans as employed with the solenoid for the head valve; and for this purpose a cable 42c`may be connected to the coil 21e and may extend to the exterior of the housing 5b. The cable 82o, and the cable 42h for the solenoid of the head valve,

may extend upwardly along the tubing 2 and at the `earths surface may he connected -to separate control means each of which may be of the type shown at Fig. 1.

When the control means for the head valve causes the coil 2lb of its solenoid to be energized;

the head valve is opened to initiate the discharge period as previously described; and the control means for the foot valve is'timed, so thatsimultaneously or just prior thereto, the coil 21cis energized to close the i'oot valve. At the end of the discharge period, the control means for the As anv'instance of this arrangement, a. hous-` ing lid for the head valve is suspended in housing 5d, from an intake conduit I8d as previously described, and a solenoid assembly such as previously described and including plunger 26d and coil 21d, is suspended from the head valve housing by .a coupling 36d. The head valve 14d closes downwardly and pressure against the valve is not balanced, the valve housing having an-finlet space 28d above the head valve-andan outlet passageway 29d below the head' valve, with the outlet'passageway leading downwardly to a-'discharge port 22d' which communicates with the expansion chamber 6d. The head valve is yieldingly seated by a spring 30d, and its depending Y stem 23d terminates in a piston 85 which is adapted for reciprocatio'n in'a cylinder 86 formed in the housing 15d below the head valve.

The stem 23d is loosely packed as shown at 8l, so as to prevent sand entering the cylinder 86 while permitting ilowof-pressure fluid between the upper en d of the cylinder and the outlet passageway 28d; and a bore 88 opens into the lower end of the cylinder 86, and is preferably provided with a check valve 88 which closesagainst eslcape of pressure from the lower end of the cylinder. 'I'he bore 88 forms a valve seat 90 and communicates with 'a bore 8| which in turn opens into the inlet space 28d, and a needle type, of pilot 'valve 82 cooperateswth the valve seat 9U and head valve deenergizes its coil 2lb so that the balanced head valve isclosed by its spring, and.

the control means for the foot valve also deenergizes the coil 21e so` that the spring Il opens the balanced foot valve in properly timed relation to the closing of the head valve, thereby inaugurating the filling period,A The timing is preferably such that the foot valve is opened just after the head valve has been closed.

It the ypressure iluid is under extremely high pressure, rthe construction as thus far describedv might require the use of such astrong spring for the head valve, in order to avoid excessive head valve leakage, as would require a more powerful solenoid than. might be practical for the restricted space available. Inox-der to avoid an excessively large solenoid and at the same timel insure operation oi.D thel head valve without excessive'leakage, the construction shown at Fig. 6 may be employed. with this arrangement the operating means for the head valve includes a solenoid such as previously described and .a piston which is actr'iated by the pressure iluid which is utilised for operating the pump. vThe solenoid controls admission ofthe pressure duid for actuating 'thepiston'whichis connected to the stem or me need-valve, vand the eieccrieei energy has a depending valve stem 93 which terminates -inthe plunger 26d of the solenoid. A spring 94 yieldingly closes the needle type pilot valve 82, which is opened against the tension of its spring uwhen the. con 21d or the so1enoid is ener.

gized, and a cable 42d-provldes` a'connection for the coil of the solenoid, and ma'y lead to a control means such as shown at Fig. 1. The foot Valve i3d may be ot the type shown at Fig. 2.

At the beginning of the illling period'the coil 21d is deenergized by the control means as explained in connection with Fig. 1. The needle valve 82 is thus closed by its spring for shutting of! the Vsupply of pressure iiuid to thelower end ofthe cylinder 88, and the pressure fluid sup-' plied to the lower end ofthe cylinder during the preceding discharge period soon leaks past the piston 85 and thence into the outlet passageway 28d, so that the spring 38d closes the head valve Ild and thenl keeps the head valve closed throughout the filling period. At the end of the lling period the control means causesvthe'coil 21d to be energized in the same manner as explained in connection with Fig. 1, thereby opening the valve 8l and admitting pressure fluid to f thelower end ofthe cylinder 88. The piston 85 is of greater area than that of the head valve piston opens the head valve' to inaugurate the .discharge period. -Pressure fluid being thus admitted to the expansion chamber ld for lifting the production fluid, back pressure builds up in the way 28d and tends to balance the head valve so that its spring 88d starts to closeA the heed valve.V But this closing movement throttles the pressure `iluid, producing a' pressurel drop through the head valve resulting in a pressure '.Ild, whereby this upward pressure against the diierential above and below the piston 85'.' :The

piston thus exerts an upward thrust, suilicient to balgnce the spring 38d. and the head valve is balanced and oats in its partially open' posieen, thereby einunuing the discharge pen'ed.

To prevent when Athe head valve is in this operr belaneedpodtion, the check valve 88 is preferably Vto insure stabilita' At the amg-toa end of the discharge period the coil 21d is again the head valve is omitted and the loperating aas-ans for the head valve is an electric; motor in lieu of the solenoid previously described.

As an instance of this arrangement the head valve Me is mounted in a valve housing |5e which is suspended in housing 5e from an intake conduit |9e as previously described, the construction providing a balanced valve adapted for I discharge of pressure uid into the expansion chambere via the discharge port 22e, when the head valve is open. 'I'he depending stem 23e of the head valve has a thread of coarse pitch',A

threaded through a nut |,0'I which is fixed against rotation or vertical movement in the lower por` tion of the valve housing 15e; and theA lower end of the valve stem is splined to a shaft |02 as shown at |03, so that the valve stem is rotated by theshaft but is free for axial movement relative thereto. A housing |04 is suspended from the valve housing 15e by a coupling 36e, and preferably has lugs 38e slidably engaging the wall of the housing 5e. An electric motor |05 is mounted in the housing |04 and rotates the shaft |02 through speed reducing gearing |06. A`

cable 42e may supply lelectrical energy to the motor |05, and preferably extends into the annular space Sand thence upwardly along thetubing string 2 to a suitable control.

At the beginning of the illling period the 'control means closes a circuit which causes rotation of the motor in one direction for rotating the shaft |02 in the direction for threading the stem 23e through the nut |0| so. as to close the head valve He. The motor is preferably a torque motor which will stop when the head valvehas been closed, and the head valve then remains closed throughout the remainder of the filling period.

At the start of the discharge period the control means closes a circuit which causes reverse rotation of the motor, thereby rotating the shaft |02 in the opposite direction and thus threadf` ing the stem 23e through the nut in the direction to open the head valve, The torque motor will stop when the head valve has beenl opened, and-the head valve then remains open throughout the discharge period, at the end of which the control means again inaugurates the lling period. The foot valve |3e employed in thisconstruction may be of. the same type as shown at Fig. 2.

The motor is preferably a three-phase motor having motor leads ||0||||| 2 connected via the control means to a source oi' electrical.

energy .l lll- I ll-I t5; and the control mea is adapted to reverse .a pair of these leads at the start of the filling period and at the start of the discharge period, for rotating the motor in opposite directions. The centr-oi means preferably also includes time relay relays, respectively openavoided.

As an instance of this arrangement the control means may include timers Afand contactors C'- which are in .general similar to corresponding parts of the control shownl at Fig. 1, the similar elements being indicated at Fig. 7.by primed reference numerals. i Wires 4:'-44' lead from the terminals lla-ifa, and

the contactors CD' withv theircontacts 56',

and the timers A'-B"with their electro-mag-y netic clutches 54' and their swinging arms 52' and their cooperating switches El', are connected to these wires as previously described. In lieu ofthe switch 49 employed -in the construction shown at Fig. 1, each4 of the contactors preferably-has a second contact H6, and

'when the coil of either of the contactors is energized, its contact 56' is open and its contact I6 is closed, and whendeenergized its contact '56' is closed and its contact H6 is open. Time delay relays VE and F are preferably employed with the contactors, and each includes a coil- Il 1, which when energized opens a switch H8 after a time interval, which may preferably be adjusted by suitable means (not shown), and which to close.- Thecoil of time delay relay Eris in circuit with wires 43'-B4', and the coil of relay F is in circuit with wires 44'-65'.' The switch ||8 of relay E is between the contact ||6 of contactor C and a wire ||9 which leads to a coil |22, the other side of which is connected to wire 44';

-and the switch H0 of relay F isl between the contact .I I6 of contactor D and` a wire |20 which 4leads to a coil |2|, the other side of which is connected to the wire 43'. The coil 2| when energized'closes switches |23|24, and the coil |22 when energized closes switches |25-|26. The switch |23 connects thev wirel 43' to the lead iii), and the switch |24. connects the wire d4' to the lead 'The switch |25 connects the wire 43' to the lead and theswit'ch |26 connects the wire 44 to the lead H0. 'I'he lead ||2 is connected to the terminal H0. i

when deenergized permits its switch ||8 1 They wiring diagram (Fig. '7) shows the position of theparts just at the start of the lling period, with the timerB' operating to determine the length of^the filling period by finally opening its' switch 5|', and with .the coil of contacter D energized so that its contact ||6 is closed, thereby energizing the coil |2| so that electrical energy is supplied to the motor |05, with the leads ||0|||||2 connected to terminals ||3'-I 4|l'||5 in the order mentioned. By this arrangement the motor is rotated in the direction to close the head valve lle and thus inaugurate the illling period, and after a time interval determined by the adjustment of relay F, and bywhich time the head valve will have been closed andff-the torque motor will have stopped rotating. the switch H8 of relay'F opens- At the end o f the lling period the arin |52'I oi timer B opens its cooperating switch 5 i thereby deenergizing the coil of contactor D and energizing'the coil of contactor C as previously explained in connection with Fig. l. The timer A then starts lto operate to determine the length of the discharge period. which is inaugurated by the closed contact llG- of contactor C, closing the circuit for the coil |22. This coilwhen energized closes the 'switches |25-|26, thus connecting the terminals ||3-| |'4| I5 to the leads ||J| I2 in that order, and thereby supply current to the motor |05 for driving it in the reverse direction. The motor thus opens the head valve to start the discharge period, and at the time lwhen the torque motor is stopped by the valve having reached its full open position, the time delay relay E operates to open its switch H8, thereby breaking the circuit for coily |22 and thus opening the switches |25|26 so as to break the main operating circuit for the motor. The head valve then remains open for the remainder of the discharge period, with the motor ||l5 idle, and until the lling period is again inaugurated by the arm 52' of the timer A' engaging and opening its cooperating switch 5|. When this occurs and as previously explained in connection with Fig. 1, the coil of contactor C is deenergized andthe coil of contactor D is again energized, so that they parts are again in the position shown in the diagram (Fig. '7), ready for thelling period.

In the modication of the invention shown at Fig. 8 the head valve is opened by operating means, actuation of which is controlled by fluid pressure other than the displacing iluid which operates the pump, and this fluid pressure-is transmitted to the operating means through a tube extending to the top of the well, and is controlled at the top of `the well so that the operating vmeans opens the head valve through-'- out the discharge period and then permit the head valve to close during the filling period,

As an instance of this arrangement the head valve |4f is mounted ina valve housing |5f which is suspended in housing 5f from an intake conduit |9f. A spring 341 tends to seat the head valve so as to shut oi! the intake'chamber 28j to the outlet passageway 231, and the outlet passageway leads downwardly toa dis.

charge port 22f-which opens into the expansion chamber 5f. 'I'he depending valve stem 23! ter-- minates in a piston |3l which is adapted for reciprocation in a cylinder |3|, and this cylinder maybe formed 'in the lower part of the valve housing |51'. Fluid pressure may be supplied to the lower end 'of the cylinder |3| v ia a tube |33, with'this tube extending to the exterior of the housing 5f and thence upwardly along the tubing string 2 to a remote control. A suitable fluid may berstored in the tube |33, with its static pressure which is directed upwardly against the ,piston |30 tending to o'pen the head valve, but the spring 34j seats the head valve against this static pressure when no additional operating pressure is exerted on the fluid in the tube |33. thereby keeping the head' valve closed during the lling period. At the start of the discharge period operating pressure is exerted onthe huid ,in the tube |33, 'thereby increasing its pressure against the piston |33 so thatV the head valve is opened against the tension of its spring, and

this operating pressure -ls then maintainedso as to keep the head valve open for the duration of the discharge period. At the end of the discharge period the operating pressure is relieved so that the spring 3l] again seats the head valve against thestatic pressure in the tube |33, thereby `again inaugurating the illling period.`

Theoperating pressure may be supplied by any suitablel means, and as an instance of this arrangement the tube |33 may communicate with Aacylinder |34 in 'which l piston-.till is torfrecip''ocation'to alternately relieve and exert 'piston when the latter is projected to exert pressure on the fluid in the tube.

y The piston |35 may be reciprocated by any suitable actuating means, and the actuating means has a suitable control whereby it projects the piston |35 for a discharge period of any desired time interval, and then permits retraction of the piston for any desired illling period.

By way of illustration the actuating means is shown as uid pressure, and for this purpose a piston |38 may be connected to the piston |35 with the piston |38 adapted for reciprocation 'in a cylinder |39, and iluid pressure may be supplied to or relieved from the cylinder |39 so as to project the piston |35 or permit its retraction. As an instance of this arrangement a three-way valve |40- may have an intake |4| connected to a source of fluid pressure, with a conduit |42 connecting the valve and the cylin.

der |39, and with an exhaust |43 leading from the valve'. A reciprocating valve head |44, when moved in one direction closes the exhaust |43 and opens the intake |4| to the conduit |42 whereby iluid pressure actuates the piston |38 so as to exert pressure inthe tube |33 for opening the head valve |4f, and when moved in the opposite direction closes the intake |4| and opens the conduit Mt to the exhaust |43 whereby fluid pressure is exhausted tromthe cylinder |39 so that the operating pressure in tube |33 is relieved, thereby permitting the head valve Hf to close. Y

Means are provided for shifting the valve head |44 vin opposite directions at predetermined time intervals, and for this purpose a solenoid |453 when energized, may shift the valve head |44 s o asto supply tluid pressure to the cylinder |39 and thereby open the head valve |4f to provide the discharge period, andv when deenergized permits `movement or the valve head |44 to shut'oii the supply oi.'l iluid pressure and exhaust the cylinderi, whereby the head valve |4f is closed to provide the lling period. The solenoid |45 may be controlled by means similar to that shown A at Fig. 1, such a control means being indicated generally at-G and showing `the knobs for its timers A" and B" whereby the time interval of the illling period andthe discharge period may be independently adjusted as previously explained, and showing the wires 41"-48" which mitted to a production string during the filling period and -is then displaced by a pressure fluid during thedischargeperiod, and the invention provides Y for alternately ,inaugurating the lling and discharge periods independently' of pressure differential between the displacing 'uid andthe iluid which is to be pux'nped.'A Consequently it is not necessary' to'aoqurately regulate the-pressure of the displacing iluid with relation to the static pressure oi' the uid which is to be pumped, in

order to produce the alternating lling and discharge and therefore the' time intervals of these alternating periods are not restricted to exactly those intervals at which the proper pressure differentials may be automatically obtained. The alternating llingand discharge periods may each consume any desired time interval, and may be independently adjusted at will.

The invention is particularly applicable to a production string for a well, with the lling and discharge periods controlled by valvular means which is preferably in the production string, adjacent the expansion chamber of the production string, with operating means for the valvular means preferably in the production string and adjacent the valvular means, and with actuation of the operating means preferably controlled by energy of a type which may be transmitted via a stationary conductor, e. g. a Wire conducting electrical energy to the operating means or atube conducting uid pressure energy to said operating means, and with the conductor preferably leading to a remote means for controlling the energy which is supplied to the conductor.

I claim:

1. In a fluid pressure displacement pump, an expansion chamber, means for alternately supplying the expansion chamber with a pressure iiuid and with a uid which is to be pumped, means adjacent the expansion chamber Afor operating the iiuid supplying means so as to independently control the time intervals during which the respective fluidsl are admitted, said operating means being adapted for control by `energy of a type Whichemay be transmitted via a stationary conductor, and means transmitting energy of said type to the operating means.

2. In a fluid pressure displacement pump, an expansion chamber, means for alternately supplying the expansion chamber with a pressure fluid and with a fluid which is to be pumped, means adjacent the expansion chamber for operating the fluid supplying means so as to vcontrol the time intervals during which the respective fiuidsare admitted, said operating means being adapted for control by energy of a type which may be transmitted via a stationary conductor, means for transmitting energy 0f said type t0 -the operating means, and means for controlling the transmission of energy so as to independently vary said time intervals for admission of the respective fluids.

3. In a fluid pressure displacement pump,'a housing forming an expansion chamber, a yalve controlling admission of fluid to the expansion chamber, a solenoid for operating the valve, the

solenoid being mounted in the housing in spaced relation from the wall thereof, the solenoid being iron clad and hermetically sealed, the wall of the housing being of magnetic material, and bridges of magnetic material between the solenoid and the wall of the housing whereby said wall forms a part of the magnetic circuit.

4. In a fluid pressure displacement pump, an expansion chamber having an inlet and an outlet n -the expansion chamber via. the inlet, a valve controlling admission of pressure iluid tothe expansion chamber, means for operating the Valve, the valve 'and its operating being mountedin the expansion chamber for iow oi' production uid therethrough.` past the operating Ameans and thence to the outlet of the expansion chamber, a stationary conductor transmitting energy to the operating means for vcontrolling its actuation, means at the top 'of the well for automatically controlling' transmission of said energy so as to independently control the time intervals during which the operating means maintains the valve open and closed respectively, the automatic control operating independently of fluid admitted to the expansion chamber, and means for adjusting the automatic control for independently varying said respective time intervals. l

5. In afluid pressure displacement pump, an expansion chamberhaving an inlet and an outletand adapted for incorporation in a well production string with its inlet providing for admission of production fluid from the well and with its outlet communicating with the production string and providing for flow of production fluid from the expansion chamber through the production string to the top of the Well, a' valvular control preventing discharge of production i'luid' from the expansion chamber via the inlet, a valve controlling admission of pressure uid to the-expansion chamber, means for operating the valve, the valve and its operating means being mgunted in the expansion chamber for ow of production 4fluid therethrough past the operating means and thence to the/outlet of the expansion chamber, and a stationary conductor transmitting energy to the operating means for controlling its actuation, the transmission of energy Via the stationary conductor being independent of pressure of' fluid supplied to the expansion chamberv via the valve. l

6. In a iluid pressure displacement pump, an expansion chamber having an inlet and an outlet and adapted for incorporation in a well production string with its inlet providing for admission of production uidfrom the well and with its outlet communicating with the production string and providing for flow of production uid from the expansion chamber through the production string to the top of the well, a valvular control preventing discharge of production uid from the expansion chamber via the inlet, a valve controlling admission of pressure uid to the expansion chamber, means for operating the valve,

the valve and its operating means being mounted in the expansion chamber for flow of production iiuid therethrough past the operating means and thence to the outlet of the expansion chamber, a stationary conductor transmitting energy to the operating means for controlling its actuation,

Vand means at the top of the well for controlling transmission of said energy, the last mentioned means operating independently of fluid admitted tothe expansion chamber.

7. In aiuid pressure displacement pump, an expansion chamber having an inlet and an outlet providing respectively for admission and discharge of a iluid which is to be pumped, a Valve adjacent .the expansion chamber for controlling admission of pressure fluid thereto, means adjacent the valve for operating'the same, a sta.-

Y tionary conductor transmitting energy to the voperating means for controlling its actuation and means for automatically controlling transmission of said energy so as to independently control the time intervals during which the operating means maintains'tlie valve open and closed respectively.` 8. In'a. uid pressure displacement pump, an

expansion chamber having an inlet and an outlet providing respectively for ladmission and discharge of a uid which is to be pumped, a Vvalve adjacenty the expansion chamber for controlling admission of pressure fluid thereto, means adjacent the valve for operating the same, a 'stationary conductor transmitting energy to the operating means for controlling its actuation, the transmission of energy via the stationary conductor being independent of pressure of iluid supplied to the expansion chamber via the valve, means for automatically controllingtransmission of said energy so as to control the time intervals during'which the operating means maintains the valve open and closed, and means for adjusting the automatic control for varying said time intervals.

9. In a uid pressure displacement pump, an

expansion chamber having an inlet and an outl let providing respectively for admission and discharge of a iluid which is to be pumped, a valve adjacent the expansion chamber for controlling admission of pressure fluid thereto, means adjacent the valve for loperating the same, a stationary conductor transmitting energy to the operating means` .for controlling' its actuation, means for automatically controlling transmission of said energy so as to independently control the time intervals during which the operating'means maintains the valve open and closed respectively, and means for adjusting the automatic control. for independently varying said respective tim intervals.

10. In a iluid pressure displacement pump, an

expansion chamber having/an inlet and an outlet providing respectively for admission and discharge of a fluid which is to be pumped, a valve adjacent the expansion chamber, means for operating the valve, said valve when open admitting pressure iiuid tothe expansion chamber and when closed preventing pressure: uid entering or escaping from the expansion chamber via said valve, a stationary conductor transmitting energy to the operating means for controlling its actuation, and means for controlling transmission of said energy so as to independently control the time intervals during which the operating means maintains the valve open and closed respectively.

11. In a fluid pressure displacement pump, an expansion chamber, a valve controlling admission of fluid to the expansion chamber, and a solenoid for operating the valve, the solenoid being mounted in the expansion chamber lin spac d relation from the wall thereof.

12. In a fluid pressure displacement pump, an expansion chamber, a valve controlling admission of fluid to the expansion chamber, a solenoid for operating the valve, thesolenoid being mounted in the expansion chamber in spaced relation from the wall thereof, the solenoid being iron clad, the wall of the expansion chamber being of magnetic material, and bridges of 'magnetic material between the solenoid and the wall oil the expansion chamber whereby said wall forms a part of the magnetic circuit.

13. In a iiuid pressure displacement pump, a.

conduit having an intake for production fluid trol thevtime intervalsduring which'the valve' is open and closed respectively.

14.1n a num pressure amplement pimp :or

a well, a production string in the well having an intake for production fluid and an intake for pressure iluid, a valve for at least one of said intakes, means in the well for operating the valve, and means for automatically controlling the operating means so as to independently control the time intervals during which the valve is open and closed respectively.

15. In a fluid pressure displacement pump, a conduit for iiuid which is to be pumped, a valve for admitting pressure fluid to the conduit when said valve is open, and preventing pressure iluid enteringv or escaping from the conduit via said valve when the valve is closed, means for operatning the valve, and means for independently controlling the time intervals during which the valve is open and closed respectively.

16r In a fluid pressure displacement pump, a conduithaving an intake for production fluid and an intake for pressure fluid, a valve for atA least one of said intakes, means for operating the valve, means for automatically controlling' the operating means so as to independently control the time'intervals during which the valve is open and closed respectively, and means for adjusting the automatic control for independently varying lsaid respective time intervals.

1'7. In a fluid pressure displacement pump, a conduit having an intake for production fluid and anintake for pressure fluid, a valve for at least one of said intakes, means for operating the valve, a stationary conductor transmitting energy -to the operating means for controlling its actuation, the transmission of energy via the stationary conductor being independent of pressure Jof fluid supplied to the conduit via the valve,

means for automatically controlling transmission of said energy so as toI control the time intervals during which the valve is open and closed respectively, and means for adjusting the automatic control for varying said time intervals.

a stationary -conductor transmitting energy, to' the operating means for controlling its actuation,

the ltransmission of energy via the stationary conductor being independent of pressure of fluid admitted to the production string, means for automatically controlling transmission of said energy so as to control the time intervals during which the valve is open and closed respectively,

and means for adjusting the automatic control for varying said time intervals.

19. In a uid pressure displacement pump, a conduit ,having an intake for Aproduction fluid and an intake for pressure iluid, a valve for at least one of said intakes, meansfor operating lthe valve, the valve and its operating means being mounted in the conduit, and a stationary conductor transmitting energy to the operating 20. In a iiuid pressure displacement pump fora well, a production string in the well having an intake for production iluid and an intake for pressure iluid, a valve for at least one of said intakes, means in the well for operating the4 valve, a stationary conductor transmitting energy to the operating means for controlling its actuation, the of energy via the sta- Sli arcaica tionary conductor being independent of pressure of duid admitted to the production string, and means for controlling transmission of energy via the stationary conductor, said last mentioned means operating independently of fluid admitted to the production string.

21. In a iiuid pressure displacement pump, a conduit having an intake for production uid and an intake for pressure uid, a valvefor at least one of said intakes, a solenoid for operating the valve, the solenoid being mounted in the conduit in spaced relation from the wall thereof, tire wall of the conduit being of magnetic material, and bridges of magnetic material between the solenoid and the Wall of the conduit whereby said Wall forms a part of the magnetic circuit.

.22. In a fluid pressure displacement pump, a conduit for fluid which is to be pumped, a valve controlling admission to the conduit of fluid which is to be pumped, a valve controlling admission of pressure fluid to the conduit, and means for operating the valves so as to alternately admit the respective fluids, said operating means providing or independently controlling the time intervalsduring which the respective iluidsare admitted.

23. In a fluid pressure displacement pump, a conduit for fluid which isto be pumped, a valve controlling admission to the conduit of :duid which is to be pumped, a valve controlling admission. of pressure fluid to the conduit, means foroperating the valves so as to alternately admit the respective iluids, said operating means providing for independently controlling the time intervals during which the respective fluids areadmitted, and means for independently varyingsaid respective time intervals.

2a. In a uid pressure displacement pump for a we1l,`a production string in the well, a valve in Eli the Well for admitting pressure fluid to the production string when thevalve is open and preventing pressure fluid entering or escaping from the production string via said valve when the valve is closed, means in the well for operating the valve, and a stationary conductor transmitting energy to the operating means for controlling its actuation, the transmission of energy via the stationary conductor being independent of pressure of uid admitted to the production string.

25. Inn a uid pressure displacement pump for a well, a production string in the well, a valve in the Well controlling admission of pressure fluid to the production string, means in the well for operating the valve by uid pressure, a valve in the well for controlling admission of said uid pressure to the operating means, and means lfor actuating the last mentioned valve independently of uid in the production string and byA energy of a type which may be transmitted via a stationary conductor, and means for transmitting energy of said type to the actuating means. Y v

26. In a fluid pressure displacement pump for a Well, a production string in the well, a conduit for supplying pressure iluid to the production string, a valve in the well controlling admission of pressure uid from the conduit to the production string, means in the well for operating the valve by fluid pressure, a second conduit containing a fluid and communicating with said Aoperating means, and means for controlling the pressure of the fluid in the second conduit, said controlling means being operable independently ,of iiuid in the production string and independ-y ently of movement of the operating means.

' aonrzafr r. 

